A Win–Win Strategy to Fabricate Double Z-Scheme Self-Supporting Integrated Photoelectrode Derived from Aniline Wastewater for Synthesis of H2O2 and Recovery of Polyaniline

Abstract

H₂O₂ and polyaniline (PANI) are important chemicals in the chemical and manufacturing industries. Herein, the concept of “turning waste into treasure” was proposed: PANI derived from aniline (ANI) wastewater was used to fabricate a double Z-scheme NiFe₂O₄–O_v@CdS@PANI photoelectrocatalytic catalyst for alleviating environmental pollution and producing H₂O₂. The double Z-scheme self-supporting integrated photoelectrode enables high light utilization and an excellent redox ability. In addition, the further designed Janus “floating” photocathode can efficiently entrap O₂ from the air and afford unidirectional transportation of O₂ from the gas-collecting side to the catalyst side during the O₂ reduction reaction. The H₂O₂ yield obtained using the Janus “floating” photocathode (264.52 mg·L^–1·h^–1) is 7.2 times higher than those of conventional “submerged” electrodes. By coupling the ANI polymerization reaction with the H₂O₂ production, the assembled electrolyzer exhibits a low cell voltage of 1.3 V vs Ag/AgCl to drive the integrated two half-reactions, the recovery rate of ANI reaches 96.5%, and the yield of H₂O₂ reached 41.9 mg·L^–1 (1.3 V vs Ag/AgCl) in solution with ANI, nearly 3 times the yield in solution without ANI.